Michael wrote: I find it just a
bit surprising you got that clearance in the first place - around
here, short IFR legs in the close vicinity of a class B are almost
always by RADAR vectors.

Yes, it's pretty typical. Sometimes you get cleared "radar vectors
direct", but much more often you get something like what I got. In
fact, this particular clearance is common enough that I use as an
exercise for people learning our GPS. Something like "CMK CMK275R
intercept SAX039R SAX" is one of the few things that's actually easier
to execute with dual VORs than with a GPS.

I agree with you that if you lost comm right off the ground, direct
CMK then as cleared would make sense. The more interesting scenario
is what happens if you check in with Departure (as we did) and he just
leaves you on the SID heading with no further instructions for a
while. At some point, you're 5 miles from SAX and 30 miles from CMK,
and it obviously doesn't make any sense to double back any more. It's
unclear where the dividing line is between those two extremes.

I don't think there's any right answer to this, it's just an
interesting exercise in PIC decision making ability to figure out what
the right thing to do is.